Determination of methocarbamol concentration in human plasma by high performance liquid chromatography-tandem mass spectrometry.

A simple and reproducible high performance liquid chromatography-tandem mass spectrometric method was developed for methocarbamol analysis in human plasma. Methocarbamol and the internal standard (IS) were extracted by a protein precipitation method. Under isocratic separation condition the chromatographic run time was 3.0 min. The calibration curve was linear over a range of 150-12,000 ng/mL with good intraday assay and interday assay precision (CV%<10.9%). The method was proven to be sensitive and selective for the analysis of methocarbamol in human plasma for bioequivalence study.